1. Technical Field
The present invention relates to an ink jet recording apparatus.
2. Related Art
Recording employing an ink jet recording system is performed by discharging small ink droplets and causing the small ink droplets to fly to cause the small ink droplets to adhere onto recording media, such as paper. Due to a recent innovative progress of the ink jet recording technology, an ink jet recording apparatus employing the ink jet recording system has been used also in the field of high definition image recording for which photo and offset printing have been used until now.
In the ink jet recording apparatus, when moisture and other volatile components contained in ink to be discharged evaporate, the viscosity of the ink increases. In recent ink jet recording, in order to perform high definition recording, the amount of ink droplets to be discharged is a very slight, e.g., several pico liters, the diameter of nozzles which discharge ink is small, and the energy required for discharging the ink droplets is also small. Since the nozzle diameter is small and the discharge energy is also small, the ink which adheres to the nozzles and undergoes an increase in viscosity cannot be eliminated, so that clogging of the nozzles is likely to occur, which sometimes results in poor ink discharge. Furthermore, fibers, paper powder, surrounding dust, and the like generated from recording media, such as paper and cloth, sometimes adhere to the formation surface (nozzle plate surface) of nozzles, which similarly hinders normal discharge of ink.
In order to prevent or reduce the poor discharge caused by the increase of in viscosity of ink and the adhesion of foreign substances to the surface of the nozzle plate described above, an ink jet recording apparatus having a wiper mechanism (recovery mechanism) has been proposed. For example, JP-A-2006-142804 discloses an ink jet recording apparatus having a cleaning mechanism employing a wiping blade. JP-A-2006-142804 discloses a technique of reducing the coefficient of friction of the wiping blade and a head (nozzle plate surface) and disposing fine particles on the surface of the wiping blade in such a manner as to protect the surface of the nozzle plate. JP-A-2009-101630 discloses, as an ink jet recording apparatus capable of simultaneously achieving low cost, high weatherability, high durability, and high reliability, an ink jet recording apparatus which has an application unit for applying a treatment liquid to a recording head or a wiping member and which carries out wiping as required, e.g., when it is judged that the head face surface (nozzle plate surface) dries.
However, the method according to JP-A-2006-142804 has had a problem in that the ink wiping properties are poor. Specifically, the method has had a problem in that, in the case of the cleaning using the wiping blade, when ink adhering to the nozzle surface, a nozzle plate cover, or the wiping blade suffers from an increase in viscosity and dries, for example, the ink cannot be removed. On the other hand, the method described in JP-A-2009-101630 has had a problem in that, although the wiping properties improve, a liquid repellent film formed on the surface of the nozzle plate deteriorates. Specifically, in the case of an ink jet recording apparatus which performs recording using an ink composition containing an inorganic pigment, there has been a problem in that the inorganic pigment present between the wiping member and the surface of the nozzle plate acts on the surface of the nozzle plate to damage the liquid repellent film and the like in cleaning (in wiping). The inorganic pigment is a component which may easily damage the liquid repellent film (a molecular film of metal alkoxide having liquid repellency or the like) typified by carbon black, titanium dioxide, and the like, for example. When the liquid repellent film is damaged around an ink discharge port, ink discharge becomes unstable, which has caused a problem in that the impact position of ink droplets varies, for example.